The present invention relates to mechanical drive devices for tools and the like, and, more specifically, to drive devices that will limit the torque being delivered by the device to an attached tool member.
Many mechanical devices are used to deliver a large amount of torque to a screw, bolt, nut, or other similar device or object. Even though there is a large amount of torque being delivered, in many situations, it is still desirous to control the precise amount of torque being delivered. For instance, too much torque may strip the object that is being driven, which would lead to the driven object becoming ineffective, such as a stripped bolt or screw. This is especially important in medical operations and procedures, where precision is critical, such as when working with spinal and skeletal structures and related devices. Thus, drivers have been developed to limit the amount of torque delivered to the driven object or device.
Because these devices are designed for precise and accurate movement, care must be maintained when assembling the driver devices. That is, the individual parts of driver must be precisely joined together. If the parts are not assembled properly, the arrangement of the driver may not deliver a proper amount of torque, which diminishes the usefulness of the driver.
Furthermore, it would be advantageous to provide a driver assembly that would allow precision testing of the driver assembly before final assembly of the driver tool. With prior art tools, a driver assembly is inserted into a handle of a driver tool, and then the precision and accuracy of the tool is adjusted. This can be time consuming, specifically when assembling a large number of tools at one time. If the driver assembly could be assembled and calibrated separately before being inserted into the handle of a driver tool, it would improve the assembly process and, also, provide a more consistently calibrated driver compared to the prior art.
Devices that deliver a limited amount of torque are generally mechanically limited in other precise functions that may be carried out with the device. For example, devices that limit the amount of torque delivered by the device and also incorporate ratcheting arrangements have limited precision. Because the individual components of the torque assembly are interacting with the components of the ratcheting portion of the tool, precision is less than ideal for both of these functions, especially after repeated uses of the device.